Physical parameters exothermic reaction

Note several features of these solutions. First the C (t) and T(t) solutions have identical shapes (but T increases as Ca decreases for the exothermic reaction) for the adiabatic reaction in these reactors or in any adiabatic reactor. If we plot Cao Ca versus T from these solutions we obtain Figure 5-8, because, by the previous arguments, this must be a straight line for any single reaction in any reactor as long as parameters do not depend on temperature or composition. Second, note that the CSTR in this example requires a shorter residence time for a given conversion than a PFTR. Third, note that the CSTR exhibits multiple values of Ca and T for a range of x. This situation is physically real and will be the subject of the next chapter. 

For the thermal runaway hazard evaluation, the "chemistry" of the exothermic reaction can be defined in terms of three sets of parameters the thermodynamic, kinetic, and physical parameters. (1) A list of some of the parameters of interest is given in Table I. 

A chemical reaction can, as a rule, be described by reaction equations that show the reactants participating in the reaction. Furthermore the reaction equations provide information about intermediates, byproducts and possible gaseous products. The possible hazard level as a result of exothermic chemical reactions is identified with a series of physical and chemical parameters that are characteristic for the reactants and equipment parameters. Especially important are the following parameters ... 

Thermal analysis methods are defined as those techniques in which a property of the analyte is determined as a function of an externally applied temperature. Regardless of the observable parameter measured, the usual practice requires that the physical property and the sample temperature are recorded continually and automatically and that the sample temperature is altered at a predetermined rate. Thermal reactions can be endothermic (melting, boiling, sublimation, vaporization, desolvation, solid-solid phase transitions, chemical degradation, etc.) or exothermic (crystallization, oxidative decomposition, etc.) in nature. Such methodology has found widespread use in the pharmaceutical industry for the characterization of compound purity, polymorphism, solvation, degradation, and excipient compatibility. ... 

From detonation physics, the charging and application of liquid explosives are not as wide as condensed explosives because liquid explosives are not compressible. Liquid explosives have an elusive outstanding feature, which is that the reactions of detonation absorb energy first, later release heat. The combination of exothermicity and endothermicity complicates the chemical reactions, and results in the parameter distribution characteristics of macrokinetics different from detonation characteristics of general high-energy explosives. 

Because the molds are heated by the exothermic PUR reaction, rapid cycling leads to high mold temperatures that can damage the mold as far as restraint by undercuts will cause stresses. Mold temperatures that increase with time are often a reason for visible surface defects and for variations in the physical properties of the product from cycle to cycle. Therefore, even for the production of low-density PUR products, it is essential to use molds that ensure reproduction of the processing parameters and permit rapid, automatic operations. 

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